1. Field of the Invention
The invention generally relates to a multilamp photoflash assembly and to a camera for use with such an assembly. More particularly, the invention relates to apparatus for advancing a plurality of flashlamps in the assembly sequentially to a firing position and for establishing an electrical connection between the respective flashlamps and a flashlamp firing circuit in the camera.
2. Description of the Prior Art
The trend in photoflash devices has been toward the use of subminiature flashlamps in compact, disposable, multilamp units to provide camera users with the advantages of greater convenience, compactness and portability. A widely used flashlamp unit of this type is known generally in the trade as a "flashcube", a specific embodiment of which is shown in U.S. Pat. No. 3,651,745, for example. The flashcube comprises a set of four flashlamps, each with its own reflector, mounted on a base and enclosed within a transparent plastic cover. Each of the lamp-reflector assemblies faces a respective one of the four side walls of the flashcube. A spindle depends from the center of the cube base to rotatably support the unit in a complementary receiving socket on a camera. In operation, the flashcube is sequentially rotated a quarter of a turn at a time, usually in response to each actuation of a film advance mechanism in the camera, to successively place unused lamps in a firing position facing the object being photographed. Each of the flashlamps consists of an hermetically sealed, light transmitting glass envelope containing a filamentary combustible material, such as shredded zirconium foil, and a combustion supporting gas, such as oxygen. In the case of flashcubes employing flashlamps that are electrically ignited (as opposed to being percussively ignited), a pair of lead-in wires extend into the lamp envelope to support a filament in combination with globules of ignition paste within the envelope. When the flashcube is in the firing position, segments of the lead-in wires disposed outside the lamp envelope are securely engaged with fixed electrical contacts in the camera socket. The electrical contacts in turn are connected by electrical conductors and a shutter actuated switch to the camera power source, usually one or more batteries. When a photographer actuates the shutter release mechanism to take a picture, by the same operation, the electrical circuit from the batteries to the ignition system in the flashlamp is closed to thereby fire the lamp. The timing of the ignition of the combustible material in the flashlamp is synchronized with the exposure of the film to obtain an efficient utilization of the light from the ignited lamp.
A more recent development in connection with compact multilamp flash units is a flashlamp magazine comprising a housing in which an endless belt carrying a plurality of flashlamps is disposed. The respective flashlamps are advanced sequentially to a firing position at a window in the housing by a sprocket wheel. The sprocket wheel engages the endless belt and is driven by a rotor activated by a film advancing mechanism in a camera, to which the flashlamp magazine is attached. As shown in U.S. Pat. No. 3,866,033, the flashlamps are percussively ignited and include associated striker springs and reflector segments. Each combination of a lamp, a striker spring, and a reflector segment is mounted on a pallet on the endless belt to provide an individual flash unit. A mechanical coupling in the magazine extends between the firing location and an access opening in the magazine. The mechanical coupling transmits a mechanical impulse from an actuating member in the camera to individually release a striker spring to fire the flashlamp in the firing position. Such magazines are particularly advantageous in that they may be readily designed to include a sufficient number of flashlamps for use with an entire roll or cartridge of film. For example, a twelve lamp magazine may be used with a twelve exposure roll of film.
When using a flashcube or other multilamp flash assembly in which the respective flashlamps are advanced sequentially to a firing position, as in the examples described above, a first device advances each of the lamps to the firing position, and a second device connects (electrically in the case of electrically ignited lamps, and mechanically in the case of percussively ignited lamps) with each of the lamps to fire the respective lamps. In the case of electrically ignited flashlamps, the second device must establish an electrical connection between a flashlamp firing circuit in the camera and the lead-in wires of a flashlamp. This is illustrated in U.S. Pat. Nos. 3,392,644; 3,473,454; and 3,651,745. The requirement of separate devices for advancing a flashlamp to a firing position and for establishing an electrical connection between the flashlamp and a firing circuit, as in the patents, is undesirable in view of the current trend toward smaller and less expensive cameras and compact multilamp flash assemblies. Such a requirement increases the size, manufacturing cost, and mechanical complexity of the camera and/or the flash assembly.